The present invention relates to apparatus for removing samples of liquids, especially milk, from a flow-metering facility, wherein a feed pump, an electromagnetically actuated metering valve closed in the rest position and at a higher level than the pump, an air eliminator and a flow-metering instrument are sequentially arrayed in the downstream direction.
Application Ser. No. 512,857 and the references cited therein, namely U.S. Pat. Nos. 2,693,196; 2,703,190; 3,538,937 and 3,746,027 show the state of the art of flow-metering facilities comprising a feed pump, an air eliminator and a flow-metering instrument sequentially arrayed in the downstream direction.
Apparatus for the purpose of continuously removing samples is required to monitor or to control, for instance as regards milk, the content in albumen or fat, the bacteriological condition, or the like.
In the apparatus of the prior art, a tap is opened, which is hooked to the feed line between the feed pump and the air eliminator, when the electromagnets and hence the metering valve are actuated, and a given amount of liquid discharges through this tap into the sample container during the opening of the metering valve. This prior art apparatus suffers from the drawback that a certain amount of liquid from the first discharge passing through the feed line remains in the metering valve after this one closes, which passes into the sample container as a sample of the subsequent (main) discharge and therefore spuriously affects the next sample of the next liquid discharge or even several subsequent samples. Depending on the number of samples associated with the individual discharges, this prior art apparatus does not always truly reflect the state of the subsequent discharge.
This spurious effect is especially significant when different suppliers are involved who provide milk to the same receiving facility and where there is a requirement to ascertain whether one or the other delivers milk of lesser quality or which is wholly unfit.